Set Appliance State:

Mains Power Off
Set Multimeter to AC Volts Set meter to measure AC Volts
CH Demand
Main switch in ON position
Summer/Winter Switch in Winter position
Heating Control Thermostat set to Maximum
WARNING! Mains voltage is expected during test, follow TOPs P4 live testing procedure
Mains Power On

Measurement:

Measure 24VAC or greater across connection 9B on Summer Winter Switch and Neutral.